1. Field of the Invention
The present invention relates to an image pickup module and a camera.
2. Description of the Related Art
A conventional image pickup apparatus includes a WL-CSP (wafer level chip size package) in which a semiconductor substrate including an image pickup device and through-hole electrodes is bonded to a light transmissive support substrate via an adhesive having an opening on the image pickup device. Japanese Patent Laid-Open No. 2009-158863 discloses an image pickup module in which a semiconductor substrate is directly mounted on a mounting substrate via solder balls. The solder balls are formed on a large area in a second main surface of the semiconductor substrate opposite to a first main surface of the semiconductor substrate on which an image pickup device is formed. Here, the inventors found the problem described below. The thickness of a semiconductor substrate of an image pickup device chip including through-hole electrodes is thinner than the thickness of a semiconductor substrate of an image pickup device chip using wire bonding so as to improve throughput and reliability of a manufacturing process of the through-hole electrodes, so the rigidity of the semiconductor substrate is low. When connecting an image pickup device chip with a mounting substrate by soldering, the melted solder starts solidifying from a portion where the temperature falls below the melting point of the solder. Therefore, in the image pickup device chip which has been cooled to a room temperature, there is a difference of contraction between a portion where the solder attaches and a portion where no solder attaches. Thus, in Japanese Patent Laid-Open No. 2009-158863, when an image pickup device is connected with a mounting substrate via solder balls arranged below a hollow portion, concaves and convexes are formed in the image pickup device chip according to positions of solders, so the flatness of a light receiving surface decreases. Therefore, there is a problem that image quality degrades.
To solve the above problem, if the thickness of the semiconductor substrate of the image pickup device chip is increased simply, the flatness of the light receiving surface is improved because the rigidity increases. However, the through-hole electrodes become difficult to be formed.
The present invention is to solve the problem of such a conventional configuration, and the present invention provides an image pickup module and a camera in which the light receiving surface of the image pickup device chip including through-hole electrodes has a good flatness and which can obtain a high quality image.